A property tax calculator for Austin, Texas is really just a formula with two honest inputs: your home’s appraised value, minus whatever exemptions actually apply to you, multiplied by the combined tax rate for your specific address. Online calculators make it look more complicated than that, mostly because the exemption side has real nuance. Here’s how to work the number yourself, and where the real numbers actually live.
The formula itself
Texas property tax bills come down to this: (appraised value minus exemptions) multiplied by (combined tax rate divided by 100) equals your annual bill. The “combined tax rate” is the sum of every taxing entity that touches your property, typically your school district, city, county, and often a community college and hospital district, each expressed as a rate per $100 of value. Inside Austin ISD, for example, the combined rate for a typical home runs around $2.05 per $100 of assessed value once every entity is added together. Outside Austin ISD, in Round Rock, Cedar Park, Leander, or Georgetown, the combined rate runs differently, generally somewhere between 1.9% and 2.4% depending on the specific city and school district combination, so the rate you plug in has to match your actual address, not a citywide average.
Step 1: find your appraised value
Your appraised value isn’t your purchase price and isn’t necessarily what you’d list the home for today. It’s the value your county appraisal district assigns as of January 1 each year, and you can look it up directly through the Travis Central Appraisal District if you’re inside Travis County, or the Williamson Central Appraisal District if you’re in Round Rock, Cedar Park, Leander, or Georgetown. Both sites let you search by address and see your current appraised value along with the history of past years.
Step 2: subtract your exemptions
This is the step most online calculators oversimplify. If the home is your primary residence, you likely qualify for a general homestead exemption, and recent constitutional amendments raised that exemption meaningfully: the school-district portion of the homestead exemption increased from $100,000 to $140,000, and homeowners who are 65 or older or have a qualifying disability get an additional $60,000 on top of that for school taxes, for a combined $200,000 exemption against the school district’s rate specifically. That exemption only applies to the school district portion of your bill, though. Your city, county, and other taxing entities set their own optional exemptions separately, some offer a percentage-based homestead exemption and some offer none at all, so you can’t just subtract $140,000 from your total appraised value across every line of the bill. Confirm the exact exemption each entity applies through your appraisal district’s property search tool rather than assuming they all match the school district’s number.
If you’ve owned and homesteaded the property for more than a year, one more piece matters: Texas caps how much your appraised value can increase for tax purposes at 10% per year on a homesteaded home, even if the market value jumped more than that. That cap only kicks in once you’ve filed your homestead exemption, which is free and due by April 30 each year through your county appraisal district.
Step 3: run the math
Take a $450,000 appraised home inside Austin ISD as an example. After the $140,000 school exemption, the school district taxes roughly $310,000 of that value at their rate. The city, county, and other entities apply their own exemptions, which may leave a slightly different taxable value for each line of the bill, then each entity’s rate gets applied to its own taxable amount and the results get added together. That’s genuinely more arithmetic than a single flat calculation, which is exactly why the appraisal district’s own online tools, rather than a generic national calculator, give you the most accurate estimate for a specific address.
It’s also worth running this math before you make an offer, not after, since property taxes typically get rolled into your monthly mortgage payment through escrow. My guide to choosing a mortgage lender covers how escrow actually works and what to confirm with your lender before you assume a listed payment estimate is accurate.
Where to get the real number instead of estimating
Both Travis Central Appraisal District and Williamson Central Appraisal District publish the actual taxing entities and rates tied to any specific property through their property search tools, and that’s a more reliable source than plugging your own numbers into a generic calculator, since it accounts for special districts like municipal utility districts that apply in some newer subdivisions and add an extra rate most citywide averages don’t capture. If you’re touring new construction in a MUD-taxed community, ask the builder directly what the current MUD rate is, since it can add a meaningful amount on top of the standard city and county rates.
This math matters even more if you’re buying as an investment rather than a primary residence, since rental property doesn’t qualify for a homestead exemption at all, which changes the calculation significantly. My breakdown of the Austin real estate investor market covers how that and other cost factors actually pencil out.
If you want the fuller picture of how city, county, and school rates actually compare across the Austin metro, I’ve broken that down separately in my guide to Austin, Texas property tax rates.
Frequently asked questions
How do I calculate my property tax bill in Austin?
Subtract your applicable exemptions from your appraised value, then multiply what’s left by your combined tax rate divided by 100. Because exemptions vary by taxing entity, your appraisal district’s own property search tool gives a more accurate number than a generic online calculator.
What is the homestead exemption worth in Texas right now?
The school-district homestead exemption is $140,000, with an additional $60,000 for homeowners 65 or older or with a qualifying disability, for a combined $200,000 against school taxes specifically. Other taxing entities, like your city and county, apply their own separate exemptions, which may be smaller or structured differently.
Does my appraised value always go up 10% a year?
No. The 10% figure is a cap, not a guaranteed increase, and it only applies to homesteaded properties. Your appraised value can rise less than 10%, stay flat, or even drop, the cap simply prevents it from increasing faster than 10% in a single year once you’ve filed your homestead exemption.
Why did my neighbor’s tax bill look different from mine on a similar home?
Exemptions are usually the reason. A homestead exemption, an over-65 exemption, a disability exemption, or a home sitting in a municipal utility district can all change the final number even between two similarly priced homes on the same street.
Do I need to reapply for my homestead exemption every year?
No, once it’s approved it generally stays in place as long as you continue to own and occupy the home as your primary residence. You only need to file again if your qualifying circumstances change, such as turning 65 and wanting to add that additional exemption.
Where to go from here
The formula is simple, the exemptions are where the real accuracy lives, and your county appraisal district’s own tools will always beat a generic calculator for a specific address. If you want help estimating what a specific home would actually cost you in taxes before you make an offer, reach out and I’m glad to run the numbers with you.
